Offshore drilling platforms are typically supported on legs which extend downward to the sea floor. On many platforms tubular legs are employed wherein an external cylindrical jacket surrounds an internal piling. The piles extend through the jackets and are driven into the sea floor for stabilization of the platform at a desired site. Annular spaces between the pilings and jackets are usually filled with grout to cement the pilings in place and provide additional stiffness.
When it is desired to relocate a drilling platform, the common practice heretofore has been to sever the legs of the platform at the sea floor by means of explosives. This approach, however, damages the legs which damages are both costly and time consuming to repair but must be done before the platform can be installed at another site. Oftentimes it has been necessary first to tow the platform to shore and then position it on land for performance of the necessary repairs. It will thus be readily appreciated that this approach to platform relocation involves manifold difficulties.
More recently, efforts have been directed toward developing a technique whereby installed pilings can be removed from the legs of offshore platforms while leaving the external jackets intact. To do so, the grout must be broken to break the bond between the jacket and the pile, after which the pile is removed without damaging the surrounding jackets. In view of the extended length of such pilings, it is desirable that any such means be capable of remote releasable connection to the piling to facilitate removal.
A need thus exists for a piling removal apparatus adapted for segmenting and lifting sections of piling from the jacket legs of offshore platforms.